Machine for flame cutting gear racks

ABSTRACT

The flame of a cutting torch is passed through a central longitudinal zone of an elongated blank so that the kerf forms two rack sections with substantially identical teeth thereon. Rack sections with such flame cut teeth are secured together in side-by-side relationship, with their teeth in endwise register, to form a rack exceeding the thickness of the blanks from which the rack sections are cut. Before flame cutting of the teeth is commenced, thin slices are flame cut from opposite faces of the blank which are to become the backs of the rack sections, to prevent warping of the flame cut rack sections along their lengths. The machine from which the rack sections are cut is provided with a carriage to support a blank for lengthwise movement through a zone in which the torch is moved back and forth crosswise of the path of blank motion. Blank supporting means on the carriage permits free lengthwise expansion of the blank toward that end thereof which is first moved into the cutting zone, as the blank becomes heated by the flame of the torch, but precludes expansion of the blank toward its opposite end.

United States Patent Maxon, Jr. et al.

MACHINE FOR FLAME CUTTING GEAR RACKS Inventors: Glenway Maxon, Jr.; William H. B. Wright, [11, both of 3129 W. Mill Road, Milwaukee, Wis. 53209 Filed: March 6, 1970 Appl. No.: 17,126

Related US. Application Data Continuation-impart of Set. No. 843,725, July 22, 1969, abandoned.

US. Cl. ..266/23 K, 74/30, 266/23 E, 266/23 R Int. Cl. ..B23k 5/00, 823k 7/00 Field of Search....266/23 K, 23 E, 23 R; 74/120, 74/12l,30, 8911,29

References Cited UNITED STATES PATENTS Oct. 3, 1972 [57] ABSTRACT The flame of a cutting torch is passed through a central longitudinal zone of an elongated blank so that the kerf forms two rack sections with substantially identical teeth thereon. Rack sections with such flame cut teeth are secured together in side-by-side relationship, with their teeth in endwise register, to form a rack exceeding the thickness of the blanks from which the rack sections are cut. Before flame cutting of the teeth is commenced, thin slices are flame cut from opposite faces of the blank which are to become the backs of the rack sections, to prevent warping of the flame cut rack sections along their lengths. The machine from which the rack sections are cut is provided with a carriage to support a blank for lengthwise movement through a zone in which the torch is moved back and forth crosswise of the path of blank motion. Blank supporting means on the carriage permits free lengthwise expansion of the blank toward that end thereof which is first moved into the cutting zone, as the blank becomes heated by the flame of the torch, but precludes expansion of the blank toward its opposite end.

11 Claims, 13 Drawing Figures PATENTEDnma 1912 SHEET 3 OF 8 IHH Q R W \J PATENTEDUCT 3 m2 SHEET 5 BF 8 rmimann m2 SHEET E OF 8 ruin Emmy Mmyzz, J2: M

PATENTEDnm 1912 3.695.599

SHEET 7 OF 8 Flmway Mmm, Jr:

' 'PATENTEDum a m2 SHEET 8 OF 8 MACHINE FOR FLAME CUTTING GEAR RACKS Like our application Ser. No. 843,725, filed July 22, 1969, now abandoned of which this application is a continuation-in-part, this invention relates to an improved method of making racks, and to a machine for flame cutting the same.

In a more specific sense, this invention is concerned with the flame cutting of racks having substantial face width and large size teeth, while achieving an accuracy that was hitherto unheard of.

It is generally recognized that large size racks can be flame cut at far less cost than is entailed when the conventional casting and machining practices are resorted to. However, because the attainment of a substantial degree of accuracy in the flame cutting of teeth in blanks of the thickness required for racks of substantial face width was heretofore considered impossible, that technique was employed only when accuracy of the rack teeth, both as to profile and pitch, was not a prerequisite.

It has now been discovered that two of the main reasons for the above mentioned deficiency of the flame cutting technique were distortion of the flame of the torch, especially when cutting the tooth tips and roots, and thermal expansion of the blank during the flame cutting operation.

The blank will expand to an extent depending upon the increase in the temperature of the metal adjoining the cut therein; and bearing in mind that the velocity of cutting must be decreased and the diameter of the torch flame must be increased to cut through the thicker blanks, the temperature of the metal will rise as a function of the thickness of the blanks being cut.

Consequently, excessive heat is generated in the interiors of substantially thick blanks during flame cutting of teeth therein, which heat cannot be dissipated sufficiently to enable thermal expansion to be controlled, even though quenching is resorted to by directing jets of cooling water onto the flame cut areas as soon as possible after they have been acted upon by the torch.

With the above in mind, it is an object of this invention to provide a method of making racks of any desired face width from laminations comprised of substantially identical rack sections, matching pairs of which can be simultaneously flame cut from single blanks having a thickness less than the finished rack, and thin enough to enable thermal expansion thereof to be readily controlled and to minimize deviation of tooth profile due to flame distortion.

Another object of the invention is to provide a method of making racks according to the manner described in the preceding object, which method sub stantially eliminates lengthwise warping of the flame cut rack sections.

In general, a flame cutting machine of the type with which this invention is concerned, is disclosed in our U.S. Pat. No. 3,306,597, issued Feb. 28, 1967. Accordin g to that patent, gear teeth are cut in the edge portion of a circular blank fixed on a blank driving spindle as a consequence of fore and aft reciprocatory motion of a cutting torch across said edge portion of the blank at a non-uniform speed during rotation of the spindle in such synchronization with respect to torch movement as to effect relative motion between the torch and the surface of the blank at a uniform rate.

It is a purpose of this invention to adapt a flame cutting machine such as that described above for the cutting of substantially identical equispaced rack teeth in an elongated blank or workpiece; and to achieve this objective through the provision of mechanism that converts rotation of the spindle into movement of a blank supporting carriage in a path which advances an elongated blank thereon lengthwise through the flame cutting zone.

More specifically, it is an object of this invention to provide a blank supporting carriage for a flame cutting machine such as described above, wherein accuracy of the teeth cut in an elongated blank on the carriage is not affected by lengthwise thermal expansion of the blank.

With these objects in mind, the invention resides in the novel method and construction, combination and arrangement of parts of the apparatus substantially as hereinafter described and more particularly defined by the appended claims. This disclosure, however, is intended merely to exemplify the invention, which is not limited to the particular structure disclosed but is susceptible of changes that lie within the scope of the appended claims.

The accompanying drawings illustrate one complete example of the method, and of the physical embodiment of the invention constructed according to the best mode so far devised for practical application of the principles thereof, and in which:

FIG. 1 is a side elevational view of a flame cutting machine embodying this invention, showing the main parts of the supporting structure for a blank to be cut;

FIG. 2 is a plan view of the machine shown in FIG. 1;

FIG. 3 is a front elevational view of the machine;

FIG. 4 is a fragmentary side elevational view illustrating an end standard that can be used to support a blank to be cut;

FIG. 5 is a sectional view taken on the line 5--5 in FIG. 1, looking at the blank supporting carriage from its rear side;

FIG. 6 is a fragmentary detail view illustrating one of the stirrup-like blank supporting hangers seen in FIG. 5 at an enlarged scale and in greater detail;

FIG. 7 is an enlarged sectional view taken on the line 77 in FIG. 2;

FIG. 8 is an enlarged sectional view taken on the line 8-8 in FIG. 2;

FIGS. 9 and 10 are fragmentary perspective views, at an enlarged scale, illustrating how racks are made in accordance with this invention;

FIG. 1 1 is a more or less diagrammatic plan view of a pair of matching rack sections illustrating in somewhat exaggerated form how the sections tend to warp along their length;

FIG. 12 is a view similar to FIG. 11, showing how straight rack sections can be cut in accordance with the method of this invention; and

FIG. 13 is a perspective view illustrating that thin slices of the blank are cut from opposite longitudinal edges thereof before flame cutting; of the rack teeth is commenced, to assure against warping of the sections.

THE METHOD Referring now to the accompanying drawings, FIGS. 9 and 10 disclose how racks, with a simple form of tooth, can be flame cut in accordance .with the method of this invention, from blanks having a rectangular cross section. As best seen in FIG. 9, the flame of a cutting torch 12 is directed downwardly through a central longitudinal zone 13 of the blank 14, to produce a kerf that is preferably but not necessarily parallel to the opposite narrow sides of the blank and defines equispaced teeth 15 therein with the teeth extending in a row lengthwise of the blank. With respect to the rectangular cross section of the blank, the flame of the torch is passed through the thickness of the blank, from one wide side of the rectangle to the other.

The teeth 15 are cut so as to be identical to one another, with straight sides, tips and roots. Accurate cutting of the teeth depends to a large degree on the care with which relative motion between the torch and the blank is effected, and it should be carried out in a way that assures uniform speed of the torch relative to the surface of the blank being cut.

The cutting of rack teeth in the central longitudinal zone of the blank produces two rack sections 16 and 17, with identical meshing teeth 15 thereon. Flame cutting is preferably commenced at one end of the blank in a way to define one-half a tooth 15 on said end of one rack section 16, and one-half a tooth space on the laterally adjacent rack section 17, as seen in FIG. 9; and with the blank free to expand lengthwise toward said one end as it is heated by the torch but held against thermal expansion in the opposite direction. It is also advantageous, though not essential, to effect flame cutting through a longitudinal zone of the blank which is at its exact center, so that flame cutting takes place at an average equal distance from the opposite longitudinal edges of the blank. With reference to the rectangular cross section of the blank, flame cutting is performed along a longitudinal zone of the blank midway between the ends of the rectangle. Such flame cutting will produce two rack sections which are identical except that their teeth are offset from one another a distance equal to one-half of the spacing or pitch of the rack teeth.

i After the torch has cut teeth in the blank along its entire length, the two rack sections 16 and 17 are separated and laid one against the other as seen in FIG. 10, with the sections so oriented that all of their teeth face in the same direction, and one section is offset lengthwise from the other by one-half of a tooth space so as to dispose the teeth of the two sections in exact endwise register. Preferably the rack section 17 is disposed with the first full tooth 15 cut thereon in endwise register with the first full tooth cut on the section 16, and with those sides of the sections that correspond to the face of the blank at which the flame of the torch entered it in mating engagement with one another. The face of the blank referred to is uppermost in FIG. 9, in which arrows 16' and 17' on the two rack sections designate the flame-entering face of the blank. The arrows 16 and 17 in FIG. 10 show how the blank section 17 was turned up and over the rack section 16, and then disposed with its teeth in register with those on the latter section.

After the rack sections 16 and 17 are laid one against the other and oriented as seen in FIG. 10, they can be secured together in any desired way as. for instance by bolts, welding or even by an epoxy bonding agent. Usually, any fractional teeth on the ends of the rack sections are cut off to leave both ends of the sections flush with one another and similar in appearance to the end of section 17 seen in FIG. 10.

One of the main features of the method described, is that the securement of the two rack sections 16 and 17 together with their teeth in endwise register produces a rack having a width equal to twice the thickness of the blank from which the rack was cut.

From the above it will also be apparent that if the proper care is exercised during the flame cutting operation, no machining, other than descaling and deburring, should be necessary on the flanks or tips of the rack teeth; and a number of rack units laminated in the manner described can be secured to a supporting surface in end to end relation to provide a rack of any desired length and at far less cost than would be entailed if more conventional machining operations hand been employed.

The act of flame cutting of the matching rack sections may have a tendency to produce lengthwise warping thereof, as seen in exaggerated form in FIG. 11. Such lengthwise warping causes the toothed edges of the sections to assume a concave curvature while the backs of the sections take on a convex curvature.

Lengthwise warping of the rack sections can be controlled and substantially completely eliminated in accordance with this invention by a flame cutting operation performed on the blank before the teeth are flame cut therein, and which involves cutting off thin slices from those faces of the blank which are to become the backs of the rack sections. FIG. 13 shows one such slice 18 which has already been flame cut from one face of the blank, with the torch in the act of cutting a similar slice 18 from the opposite face of the blank. The outlines of the rack teeth 15 to be thereafter cut in the portion of the blank medially between said faces thereof are shown in construction lines.

We are unable to explain exactly why the flame cutting of thin slices from opposite sides of the blank in the manner described above prevents lengthwise warping of the matching rack sections. However, it has been ascertained that much less warping occurs when flame cutting mild steel blanks than when rack teeth are cut in heat treated steel blanks.

It should be apparent that racks can be flame cut with teeth having rounded tips and gullets of corresponding concavity at the roots of the teeth, for greater strength; and that the teeth may have cycloidal or straight flanks and faces that are either symmetrical or non-symmetrical. With any non-symmetrical tooth form, however, the racks should be flame cut so that the sections from which they are laminated can be oriented in one way or another to bring their teeth into the end to end matching or congruent relationship in which they complement one another to severally or collectively provide the teeth of the finished rack.

Persons skilled in the art will also appreciate that the above described method also makes possible 1 the production of flame cut racks having a face width greater than twice the thickness of the blank from which the racks are cut. This of course will require the cutting of the same style and size of teeth in each of two or more blanks, one blank at a time.

There may also be times when it may be necessary or desirable to effect flame cutting along one marginal edge portion of a blank. At such times, the narrow piece is discarded, and the wider piece provides a rack section that can be welded or secured to others like it, with its teeth in endwise register and congruent therewith, to produce a rack of the desired width THE MACHINE The flame cutting machine illustrated in the drawings is nearly identical to that shown and described in our aforesaid U.S. Pat. No. 3,306,597. Inasmuch as that patent can be referred to for a complete disclosure of the machine, it will suffice to here only briefly describe the same.

One major and important difference is that the present machine is provided with structure for supporting an elongated blank 14 and for guiding the same for endwise horizontal movement through a flame cutting zone 21. The flame cutting zone 21 is defined by the path of fore and aft movement of the cutting torch 12. The torch is mounted on the forward end of a carriage 22 which is constrained to reciprocatory motion along a horizontal path normal to the path of endwise movement of the blank 14 through the cutting zone; and the torch is positioned to direct its flame downwardly.

The torch carriage 22 is mounted on the top of a table 23, and the torch 12 thereon operates at a location forwardly of the table and beneath the level of its top. The carriage is driven bodily back and forth in consequence of rotation of a so-called contour cam 24 mounted on a shaft 25 that is driven from the output shaft of a Graham type transmission 26, which in turn is driven from a prime mover such as an electric motor 27. The cam shaft 25 also has a speed regulating cam 28 fixed thereon, connected by a follower and linkage 29 with the speed adjusting shaft 30 of the Graham transmission. Accordingly, the speed of the transmission is varied in accordance with the contour of the cam 28.

The transmission 26 and motor 27 are part of a power unit generally designated 31, and which further includes change gearing, not shown, by which the output shaft of the transmission is drivingly connected with a blank drive spindle 32. The blank drive spindle is mounted in a bearing structure 33 and constrained thereby to rotate on a vertical axis spaced a distance ahead of the table 23. The blank drive spindle is connected with the change gearing of the power unit as by means of a worm wheel 34 on the lower end of the spindle, and a worm 35 on a shaft 36 that extends rearwardly to the power unit.

Though not essential, the axes of the blank drive spindle 32 and of the camshaft 25 lie in a common vertical plane which also contains the axis of the vertically disposed torch, and which plane is normal to the path of movement of the blank lengthwise through the flame cutting zone 21.

In the machine of our aforesaid patent, the spindle 32 was utilized to impart rotation to a more or less circular blank while the torch 12 was driven fore and aft over the peripheral edge portion of the blank to cut gear or sprocket teeth therein. In the present case, however, the spindle 32 has a blank drive gear 38 fixed thereon to rotate therewith; and a disc-like shroud 39 is also fixed to the spindle beneath the gear.

The gear 38 is located only slightly below the underside of an elongated fixed beam 40 which is mounted horizontally crosswise of the path of torch motion, so as to be parallel to the path the blank 14 is moved through the flame cutting zone 21. The beam is rigidly supported by a pair of spaced apart standards 41, which are fixed to the opposite sides of the base of the bearing structure 33. The ends of the beam can also be supported by a pair of end standards 42 spaced outwardly from the standards 41. The end standards 42 are primarily used for setting up and preparing the apparatus for flame cutting racks, and for storage of the blank supporting structure when gears are to be cut by the machine. They are not necessary and can be removed before actual flame cutting of racks is commenced.

The beam 40 provides a support for a movable blank supporting carriage generally designated 44. For that purpose, the beam has an elongated track 45 fixed to its top, lengthwise thereof, from which the blank supporting carriage is suspended. The main component of the blank supporting carriage comprises an elongated beam 46, located alongside and parallel to the beam 40, between the latter and the torch 12. A number of bearing members 47 are fixed to the top of the beam 46, at spaced apart locations along its length, and each such bearing member freely rotatably carries a pair of rollers 48 and 49. The rollers 48 track upon the top of an over head rail 45, while the rollers 49 engage the side of said rail remote from the torch 12. Another rail 50 fixed to the carriage beam 46 adjacent to its bottom engages the periphery of the disc-like shroud 39, and cooperates with the rollers 48 and 49 to hold the carriage in a stable state as it is translated along the overhead rail 45. The tendency for the beam 46 to swing toward the beam 40, of course, holds the lower rail 50 in engagement with the periphery of the shroud.

A number of rollers 51 freely rotatably mounted on the underside of the stationary beam 40 are also provided to track upon the lower rail 50 and thus help to stabilize the blank supporting carriage.

Rotation of the spindle 32 is translated into endwise feed motion of the carriage 44 by means of a rack 52 fixed to the carriage beam at the top of the rail 50, and having teeth in mesh with those on. the blank drive gear 38.

The blank supporting carriage 44 is provided with a number of hangers to support an elongated blank 14 for travel through the cutting zone. One such hanger 54 is fixed to the carriage beam 46 by screws 55, while the remaining hangers 56 are suspended from the shafts 57 carrying the top rollers .48, for swinging motion about horizontal axes parallel to the path of motion of the torch carriage 22. Thus, the hangers 56 can swing lengthwise of the beam 46, along the path of travel of the blank supporting carriage. As illustrated, there can be two such swingable hangers 56, mounted in spaced relation to one another and forwardly of the fixed hanger 54 with respect to the direction in which the blank supporting carriage is driven by the spindle 32.

Each of the hangers 54 and 56 is in the form of a stirrup 58in which the blank 14 is seated. The stirrups are located at the side of the carriage beam 46 remote from the fixed beam 40, and support the blank 14 for movement directly under the torch 12. Each stirrup has opposite narrow pads 59 spaced apart transversely of the path of travel of the blank through the cutting zone, upon which the blank rests with only a limited area of its marginal edge portions engaging the pads. The bight portions 60 of the stirrups which extend between the pads 59, are recessed downwardly away from the underside of the blank and provided with steeply sloping sides to limit direct impingement of the flame of the torch thereagainst.

The stirrups are shaped to have the blank fit between their upstanding legs 61 and 62, and screws 63 passing through the legs 61 and bearing upon the adjacent side of the blank 14 hold the latter against the inner surfaces of the legs 62. Those surfaces are formed to accurately define the position of the blank relative to its carriage and to cause the blank to be held exactly parallel to the carriage beam 46.

Referring now to FIGS. 2 and 5, it will be seen that the blank drive gear 38, when rotatably driven in the direction of the arrow (FIG. 2) will impart movement to the blank supporting carriage and the blank thereon downwardly as viewed in FIG. 2, or to the right as viewed in FIG. 5. FIG. 2, however, shows the blank supporting carriage in a retracted position, before flame cutting is commenced. Actual cutting, of course, will take place as indicated by the construction line representations of teeth in the leading end portion of the blank 14.

During cutting of the simple rack teeth seen in FIGS. 9 and 10 and shown by way of illustration in construction lines in FIG. 2, the cam 24 will cause the torch to be held stationary for a time at each of its limits of reciprocatory motion while the blank is advanced at a uniform maximum speed, to thereby effect cutting of straight tips on the teeth on each rack section. The blank will be advanced at a slower speed while the torch is moved fore and aft to effect flame cutting of the straight but slanted flanks of the teeth. During such cutting the two cams 24 and 28 and the change gears (not shown) through which the blank drive gear 38 is rotated, all cooperate to assure that the speed of the torch relative to the surface of the blank being cut will be substantially uniform.

The motions of the blank and of the torch are somewhat different, of course, when flame cutting teeth with curved faces and flanks, and with curved tips and gullets.

FIG. 5 best illustrates one of the most important features of the invention, namely, that the blank being cut is free to expand lengthwise in the direction of travel of the blank through the cutting zone, due to heating of the blank by the flame of the torch, while being restricted against thermal expansion in the opposite direction. It is for this reason that the trailing end of the blank is held in engagement with an adjustable stop in the form of another screw 65 threaded into a bracket 66 fixed on the hanger 54.

Due to the end stop 65, therefore, all lengthwise thermal elongation of the blank due to the heat of the torch must take place in the direction of blank travel through the cutting zone. Such motion of the blank relative to its carriage is possible by reason of the fact that the blank carrying hangers 56 are free to swing in the counter-clockwise direction about their supporting shafts 57, as exaggeratedly shown in FIG. 5.

This feature is highly important, since it assures against inaccuracies that would otherwise result during flame cutting, if the blank were free to expand lengthwise in both directions.

If desired, the machine can be equipped with torches (not shown) to preheat the central zone of the blank at its top and bottom before rack teeth are cut therein; and quenching nozzles (not shown) can similarly direct streams of cooling water onto the central zone of the blank after the teeth are cut therein. One way in which such preheating and cooling can be accomplished is disclosed in US. Pat. No. 2,816,848, issued Dec. 17, 1957, to Glenway Maxon, Jr.

From the foregoing description, together with the accompanying drawings, it will be apparent to those skilled in the art that this invention provides a novel method of making racks and featuring a machine by which the teeth of the racks can be flame cut.

Those skilled in the art will also appreciate that the invention can be embodied in forms other than as herein disclosed for purposes of illustration.

The invention is defined by the following claims:

1. In a machine for flame cutting racks from elongated blanks, the combination of:

A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone;

B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a straight path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank;

C. blank advancing means for moving a blank along said straight path;

D. a prime mover;

E. and drive means driven from the prime mover and operatively connected with the carriage and the blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.

2. The flame cutting machine of claim 1 further characterized by said drive means comprising:

A. a rotatable blank drive spindle;

B. a gear fixed on said spindle to rotate therewith;

C. and an elongated rack on the blank supporting means, with which said gear meshes, said rack being disposed parallel to said straight path.

3. In a machine for flame cutting racks from elongated blanks, the combination of:

A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone;

B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movement of the torch and the blank;

C. blank advancing means for moving a blank along said second path, comprising 1. a blank drive spindle rotatable about an upright axis forwardly of the cutting torch and so located that the blank supporting means is between the spindle and the torch,

2. a gear fixed on said spindle to rotate therewith,

3. and an elongated rack mounted on the blank supporting means at a location between the spindle and a blank on the blank supporting means, and with which said gear meshes, said rack being disposed normal to said first path;

D. a prime mover;

E. and drive means driven from the prime mover and operatively connected with the carriage and with said spindle to drive the same, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.

4. In a machine for flame cutting racks from elongated blanks, the combination of:

A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone;

B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth out therein as a consequenceof said movements of the torch and the blank, said blank supporting means comprising 1. stationary supporting structure disposed forwardly of the torch carriage and including an elongated horizontal beam normal to the path of movement of the torch carriage,

2. a second movable carriage supported by said beam for movement lengthwise thereof and along said second path,

3. and means on said second carriage for holding an elongated blank in position thereon, parallel to said beam;

C. blank advancing means for moving said second carriage along said second path;

D. a prime mover;

E. and drive means driven from the prime mover and operatively connected with the torch carriage and with the blank advancing means, said drive means so synchronizing the movements of the torch carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.

5. The flame cutting machine of claim 4 further characterized by:

A. said stationary supporting structure comprising an elongated track parallel to said beam;

B. said second movable carriage comprising 1. a second elongated beam parallel to said first designated beam,

2. a number of bearing members carried by said second beam at locations spaced apart lengthwise thereof,

3. and rollers mounted on said bearing members and engaging said track to support said second beam for lengthwise movement along the track.

6. The flame cutting machine of claim 4 further characterized by said second movable carriage comprising:

A. a number of hangers spaced apart longitudinally of said beam, and by which a blank can be supported and moved along said second path through the cutting zone;

B. one of said hangers which is farthest from the cutting zone at the start of flame cutting having means thereon to hold a blank fixed with respect to said second carriage,

C. and those hangers which are located forwardly of said one hanger being mounted on said second carriage for movement relative thereto along said second path so as to allow a blank carried by said second carriage to freely expand lengthwise away from said one hanger as the blank is heated by the flame of the torch.

7. ln a machine for flame cutting racks from elongated blanks, the combination of:

A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone;

B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank, said blank supporting means comprising an elongated beam constrained to move lengthwise of said second path and having a rack fixed thereto;

C. blank advancing means for moving said beam lengthwise of said second path;

D. a prime mover;

E. and drive means driven from the prime mover and operatively connected with the carriage and the blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed, said drive means comprising a gear rotatable on a fixed axis and meshing with said rack.

8. In a machine for flame cutting racks from elongated blanks, the combination of:

A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone;

B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth out therein as a consequence of said movements of the torch and the blank, said blank sup porting means comprising 1. a pair of parallel horizontal beams, one being stationary and having an elongated track fixed to its top,

2. the other beam being adapted to support the blank and being movable lengthwise along said second path and laterally adjacent to the stationary beam,

3. rollers carried by the movable beam and riding on the top of the track and on one side thereof which is remote from the movable beam;

4. and cooperating guide means carried by said beams and engageable with one another along an elongated path parallel to said movable beam and adjacent to its bottom;

C. blank advancing means for moving said movable beam along said second path;

said blank supporting structure comprises means providing for flame induced lengthwise expansion of the blank in said one direction relative to its supporting structure, and to preclude such motion of the blank in the opposite direction.

D. a prime mover;

E. and drive means driven from the prime mover and operatively connected with the carriage and with said blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative straight path lengthwise of the blank supporting structure;

I E. means on the torch supporting structure mounting the torch for reciprocatory motion between 11. In a machine for flame cutting racks from elongated blanks, the combination of:

defined limits along a path extending crosswise of 35 the path of translatory movement of said one supporting structure and over the blank, so that relative movement between the torch and the blank as a consequence of said reciprocatory motion of the A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone;

motion between the torch and the surface of the B. blank supporting means by which an elongated blank at a substantially uniform speed. blank can be supported and guided for lengthwise 9. In a machine for flame cutting racks from elon-, movement in one direction along a straight second gated blanks, the combination of: path transverse to the path of torch molvement and A. elongated supporting structure for supporting an eadmg through the cuttmg Zone: to spaced elongated blank in a horizontal attitude while teeth cut therem as a consequence 9 move Spaced teeth are cut therein; ments of the torch and the blank, said blank supa cutting torch; porting means comprising means acting on the C. supporting structure for the torch; blank to provlde fonflame induced lengthwise exmeansmouming one of said Supporting Structures pansion thereof in said one dlrection relative to the for bodily translatory movement along a defined blank suppomng means wh'le precludmg Such pansive motion of the blank in the opposite direction;

C. blank advancing means for moving a blank along said second path;

D. a prime mover;

E. and drive means driven from the prime mover and operatively connected with the carriage and the blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative torch while said one supporting structure is moved 40 bodily in one direction with respect to the length mono between h torch and the surface of the of the blank results in the cutting of spaced teeth in blank at a substamlany umform Speedthe blank; 

1. In a machine for flame cutting racks from elongated blanks, the combination of: A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone; B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a straight path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank; C. blank advancing means for moving a blank along said straight path; D. a prime mover; E. and drive means driven from the prime mover and operatively connected with the carriage and the blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.
 2. The flame cutting machine of claim 1 further characterized by said drive means comprising: A. a rotatable blank drive spindle; B. a gear fixed on said spindle to rotate therewith; C. and an elongated rack on the blank supporting means, with which said gear meshes, said rack being disposed parallel to said straight path.
 2. a gear fixed on said spindle to rotate therewith,
 2. a number of bearing members carried by said second beam at locations spaced apart lengthwise thereof,
 2. the other beam being adapted to support the blank and being movable lengthwise along said second path and laterally adjacent to the stationary beam,
 2. a second movable carriage supported by said beam for movement lengthwise thereof and along said second path,
 3. and means on said second carriage for holding an elongated blank in position thereon, parallel to said beam; C. blank advancing means for moving said second carriage along said second path; D. a prime mover; E. and drive means driven from the prime mover and operatively connected with the torch carriage and with the blank advancing means, said drive means so synchronizing the movements of the torch carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.
 3. rollers carried by the movable beam and riding on the top of the track and on one side thereof which is remote from the movable beam;
 3. and rollers mounted on said bearing members and engaging said track to support said second beam for lengthwise movement along the track.
 3. and an elongated rack mounted on the blank supporting means at a location between the spindle and a blank on the blank supporting means, and with which said gear meshes, said rack being disposed normal to said first path; D. a prime mover; E. and drive means driven from the prime mover and operatively connected with the carriage and with said spindle to drive the same, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.
 3. In a machine for flame cutting racks from elongated blanks, the combination of: A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone; B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movemenT in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movement of the torch and the blank; C. blank advancing means for moving a blank along said second path, comprising
 4. In a machine for flame cutting racks from elongated blanks, the combination of: A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone; B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank, said blank supporting means comprising
 4. and cooperating guide means carried by said beams and engageable with one another along an elongated path parallel to said movable beam and adjacent to its bottom; C. blank advancing means for moving said movable beam along said second path; D. a prime mover; E. and drive means driven from the prime mover and operatively connected with the carriage and with said blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.
 5. The flame cutting machine of claim 4 further characterized by: A. said stationary supporting structure comprising an elongated track parallel to said beam; B. said second movable carriage comprising
 6. The flame cutting machine of claim 4 further characterized by said second movable carriage comprising: A. a number of hangers spaced apart longitudinally of said beam, and by which a blank can be supported and moved along said second path through the cutting zone; B. one of said hangers which is farthest from the cutting zone at the start of flame cutting having means thereon to hold a blank fixed with respect to said second carriage, C. and those hangers which are located forwardly of said one hanger being mounted on said second carriage for movement relative thereto along said second path so as to allow a blank carried by said second carriage to freely expand lengthwise away from said one hanger as the blank is heated by the flame of the torch.
 7. In a machine for Flame cutting racks from elongated blanks, the combination of: A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone; B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank, said blank supporting means comprising an elongated beam constrained to move lengthwise of said second path and having a rack fixed thereto; C. blank advancing means for moving said beam lengthwise of said second path; D. a prime mover; E. and drive means driven from the prime mover and operatively connected with the carriage and the blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed, said drive means comprising a gear rotatable on a fixed axis and meshing with said rack.
 8. In a machine for flame cutting racks from elongated blanks, the combination of: A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone; B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank, said blank supporting means comprising
 9. In a machine for flame cutting racks from elongated blanks, the combination of: A. elongated supporting structure for supporting an elongated blank in a horizontal attitude while spaced teeth are cut therein; B. a cutting torch; C. supporting structure for the torch; D. means mounting one of said supporting structures for bodily translatory movement along a defined straight path lengthwise of the blank supporting structure; E. means on the torch supporting structure mounting the torch for reciprocatory motion between defined limits along a path extending crosswise of the path of translatory movement of said one supporting structure and over the blank, so that relative movement between the torch and the blank as a consequence of said reciprocatory motion of the torch while said one supporting structure is moved bodily in one direction with respect to the length of the blank results in the cutting of spaced teeth in the blank; F. a prime mover; G. and means associated with the prime mover for producing and so synchronizing said movements of the torch and said one supporting structure as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed.
 10. The flame cutting machine of claim 9 wherein said blank supporting structure comprises means providing for flame induced lengthwise expansion of the blank in said one direction relative to its supporting structure, and to preclude such motion of the blank in the opposite direction.
 11. In a machine for flame cutting racks from elongated blanks, the combination of: A. a carriage constrained to reciprocatory movement along a first path, and having a cutting torch mounted thereon for fore and aft movement therewith in a cutting zone; B. blank supporting means by which an elongated blank can be supported and guided for lengthwise movement in one direction along a straight second path transverse to the path of torch movement and leading through the cutting zone, to have spaced teeth cut therein as a consequence of said movements of the torch and the blank, said blank supporting means comprising means acting on the blank to provide for flame induced lengthwise expansion thereof in said one direction relative to the blank supporting means while precluding such expansive motion of the blank in the opposite direction; C. blank advancing means for moving a blank along said second path; D. a prime mover; E. and drive means driven from the prime mover and operatively connected with the carriage and the blank advancing means, said drive means so synchronizing the movements of the carriage and the blank advancing means as to effect relative motion between the torch and the surface of the blank at a substantially uniform speed. 